The invention relates to a dosing device for bulk materials, particularly hard to flow and sticking bulk materials that tend to form bridges in a supply container.
Dosing devices are used in industrial or commercial application processes in which predetermined quantities of bulk materials are, per unit of time, discharged, or are added, or are weighed. Thereby, the bulk materials are withdrawn from a supply container with the aid of discharge devices or conveyor devices and supplied to the scheduled processes.
The conveyor devices are arranged, as a rule, below the supply container so that the bulk materials mostly reach the conveyor device under the influence of gravity. Thereby, problems may occur during the continuous feeding from the supply container into the conveyor, particularly in connection with bulk materials that hardly flow, stick together and form bridges. Therefore, it is frequently necessary that the dosing devices are equipped with stirring mechanisms in the supply containers. During maintenance work or when a change is made from one bulk material to another, the dosing devices should be cleaned. Therefore, the discharge area of the dosing container must be accessible without any large assembly effort.
European Patent Publication EP 0,486,424 discloses a dosing apparatus for supplying bulk materials, constructed of different structural units. The bulk material supply container forms a structural unit with a horizontal stirring device and with a discharge mechanism. A further structural unit is formed by the drives and the weighing section. The first mentioned structural unit can be separated from the second structural unit without a large mounting effort, whereupon the unit can be cleaned quickly and without a prolonged down time. This operation is possible only for smaller dosing devices because it is always necessary to remove the entire bulk material container with the entire stirring mechanism and with the discharge device for the cleaning operation. Such smaller dosing devices are not required for statical reasons to be installed in a fixed machine frame.
German Patent Publication DE 195 01 179 discloses a dosing device for bulk materials in which a separate intermediate container is arranged above a discharge mechanism. The intermediate container comprises a vertical stirring mechanism and can be released from its drive and from the discharge mechanism by a vertical plug-in connection. However, there is no connection between the stirring mechanism and a supply container attachable above, so that it is possible that the bulk material sticks to the supply container, or a separate stirring mechanism must be arranged there.
A company brochure entitled xe2x80x9cMultifeed 2001xe2x80x9d, No. F9106, published June 1991, by the Firm Carl Schenck AG of Darmstadt, discloses a dosing device for bulk materials, which device forms part of a differential dosing scale. This differential dosing scale is constructed in a modular manner and is equipped with laterally tiltable structural units below a supply container installed in a fixed position. Such a structure provides a better accessibility during service or cleaning operations. One construction variant suitable for hardly flowing bulk materials is disclosed in which a vertical stirring mechanism is arranged in the rigidly mounted supply container. The vertical stirring mechanism extends all the way to the bottom of an intermediate container which is removably secured below the supply container. If service and cleaning operations must be done, it becomes necessary to release a discharge mechanism which is arranged under the intermediate container. The discharge mechanism is then tiltable laterally below the intermediate container. Only then it is possible to take off the intermediate container with the aid of a clamping strap. However, the intermediate container can be taken off only in the downward direction because of the vertical stirring section inside thereof. For this purpose a vertical disassembly space must be provided which requires a height corresponding approximately to the height of the intermediate container. Detaching of this type of construction is relatively labor intensive when service or cleaning operations must be done. Additionally, it requires a vertical structural space that is not insignificant.
Another construction variant of the differential dosing scale has but one horizontal stirring device in the intermediate container instead of a vertical stirring device in the supply container and in the intermediate container. The horizontal stirring device has its own drive. However, hardly flowable bulk materials can adhere or form bridges in the supply container, whereby a uniform dosing is impaired. Particularly, it is frequently not possible with such horizontal stirring mechanisms when dosing strongly adhering powders, to separate these all over from the margin and bottom areas because the stirring components cannot reach these areas. Bulk materials such as groceries remaining in these areas can easily over-age during prolonged dosing durations or they may harden or they may impair the dosing operation in another manner so that intermediate service or cleaning operations are necessary.
In view of the above it is the object of the invention to provide a dosing device that is easily accessible and that assures a uniform throughflow of all bulk materials through the bulk material containers with most simple structural components.
This object is achieved by the invention with a bulk material dosing device comprising a multi-part bulk material container, a stirring mechanism rotatably mounted in said multi-part bulk material container, a drive for rotating said stirring mechanism, said multi-part bulk material container comprising at least a supply container part and a removable dosing container part, said stirring mechanism comprising a plurality of stirring sections, wherein at least one stirring section is rotatably positioned in said dosing container part and another separate stirring section is rotatably positioned in said supply container part, and a releasable coupling operatively connecting said plurality of stirring sections to each other in a force transmitting manner for driving said stirring mechanism, and releasable means for laterally removing said dosing container part together with its stirring section.
The invention has the advantage that by using a vertical stirring mechanism, the marginal areas and the bottom areas of the bulk material container having a rotational symmetry all the way to the outlet opening are reachable by stirring mechanism wings. Thus, no bulk material remainders can adhere or spoil. Simultaneously, a homogeneous bulk material throughflow is achievable because the uniform rotational motion of the wings of the stirring device across the direction of the force of gravity reaches all container areas in the same force direction, whereby the flow velocity is uniformly influenced in all areas.
The invention has further the advantage that due to the stirring device coupling the fixed installed stirring device areas and container areas do not need to be disassembled with the aid of tools when cleaning or service operations are necessary so that prolonged down times of the dosing device are avoidable. At the same time the discharge device with a portion of the bulk material container is horizontally laterally removable due to the stirring device coupling. As a result, advantageously no additional vertical assembly space is required for dosing components mounted in the direction of the gravity force. Furthermore, the stirring coupling permits driving both stirring sections through the force transmitting coupling with but one stirring drive so that, advantageously, a separate stirring device drive for the removable stirring device section and container part is obviated.
According to a special embodiment of the invention the discharge apparatus is horizontally slidable into a discharge head that is mounted in a fixed position. This feature advantageously permits separating structural components which require service or cleaning, in a simple manner from the side of the dosing device that faces away from the process. Such separating is achievable without any substantial assembly effort and expense.